The Southern Development Region (RDS) of the Republic of Moldova represents one of the most important country’s regions, its surface being 9.29 ths. km2 or about 27.4% of the total. About 1170 rivers with a length of 4124.7 km flow within the region. Large ones are transbondary rivers Dniester and Prut with length of 189 km and 256 km. Other rivers are Ialpug with a length of 113 km but also its tributaries Lunga of 81 km, Ialpugel of 53.2 km, Salcia Mare of 45.2 km. Also, within the RDS the lower course of the Botna river is located with a length of 55.8 km as well as the middle course of the Cogalnic river with a length of 55.8 km and the upper and middle course of the Cahul river of 48 km, both continue in Ukraine. Monitoring on small and medium rivers was performed since 50s-60s of the last century on Botna, Cogalnic and Taraclia, and from the end of 70s on Salcia Mare and Lunga. Most of observation stations were closed 10-15 years ago, except the one on Botna. Basing on monitoring data, main hydrological characteristics were evaluated. Thus, the Botna River has an average water flow of 0.77 m3/s, water volume of 24.3 mil. m3, runoff of 20 mm at the Causeni. The tendency is stable, no increase of decrease is observed. Main water resources are formed in spring with a share of 36%, followed by summer, winter and autumn. The hydrological characteristics of Cogalnic are 0.26 m3/s, 8.26 mil. m3, 46.1 mm at Hancesti station. The annual flow dynamic is evaluated by a very slow decreasing trend. Seasonal distribution is the same as in case of Botna river. The flow of two tributaries of the Ialpug river: the Salcia Mare and the Lunga river, has a strong decreasing trend, the multiannual flow hydrograph being clearly divided in two parts, approximately at year 1994. Thus, the averages for two periods of the Salcia Mare are 0.4 m3/s and 0.2 m3/s, 28.9 mm and 14 mm, 12.6 mil. m3 and 6.22 mil. m3. In case of Lunga river the averages are 0.2 m3/s and 0.07 m3/s, 16.7 mm and 6.2 mm, 6.2 mil. m3 and 2.22 mil. m3. Seasonal flow of the two rivers does not show any high differences in flow formation; about 30% of runoff is generated in spring, 25 % in summer and winter each, 20% in autumn. The Taraclia river flow dynamic differs from the others, the tendency being visibly increasing. The averages of hydrological characteristics of this river are 0.18 m3/s, 5.76 mil. m3, 55.9 mm at Taraclia station. Also, in case of Taraclia, the highest share of flow is formed in summer - 38%, being followed by winter and spring - 23% each, and autumn - 17%. Overall, at the regional level, analysis of the monthly runoff shows that the most important water resources are formed in the spring period followed by the summer and winter period. The smallest resources are formed in autumn. The climate changes of the last decades have determined the reduction of water resources, and in case of the southern rivers, this reduction is about 50%.